RESISTANCE OF CONCRETE INCORPORATING PORTLAND LIMESTONE CEMENT TO SULFURIC ACID

摘要

Concrete has long been the most popular choice for constructing key infrastructural elements such as sewer pipes, water treatment facilities, industrial floors and foundations. However, many field cases from all around the world have shown that concrete elements in these environments are severely damaged due to biogenic and/or chemical sulfuric acid attack. Since high alkalinity is required for the stability of the cementitious matrix, concrete is highly prone to acid attacks, which decalcify and disintegrate the hydrated cement paste to various levels based on exposure conditions and type of concrete. Numerous studies have been conducted to enhance the durability of concrete and understand the influence of key mixture design parameters on its resistance to sulfuric acid attack. Yet, there is dearth of information on the behaviour of a new type of cement in North America, which contains a high level (5 to 15%) of interground limestone powder (portland limestone cement: PLC), under acidic attack. Hence, the aim of this study is to investigate the effect PLC with or without supplementary cementitious materials (SCMs) on the durability of concrete exposed to acidic attack. The study comprised 13 weeks (90 days) immersion of test specimens in 5% sulfuric acid solutions with pH in the range of 0.1 to 2.5. Physical and microstructural results reveal that PLC may improve the resistance of concrete to sulfuric acid attack, whereas the SCMs had a mixed effect on the results.